Ford's Mark Winterbottom cools down with an ice bath in the team truck. Picture: Gregg Porteous Source: The Daily Telegraph

CABIN temperatures are set to soar above 65C at the Sydney 500 today, sparking health concerns for the V8 field with leading Ford driver Will Davison predicting several drivers will be "taken away in the back of an ambulance.

As champion-in-waiting Jamie Whincup began his crowning weekend with a torrid day of practice on the streets of Olympic Park, several V8 stars said the sweltering Sydney heat would place drivers in danger of passing out because of dehydration.

With temperatures inside the V8 cabins predicted to be up to 30C higher than the air temperature - which is expected to reach 40C at Sydney Olympic Park in the midst of a heat wave - drivers were ordered to drink 15 litres of water last night and will spend the morning in ice baths and food freezers.

Some of the drivers will even strap styrofoam coffee cups to their feet to stop scorching-hot brake pedals from burning them.

Ford driver Davison predicted the heat would get the better of several drivers with no air conditioning inside the cars.

"The heat is certainly a concern but we are just going to have to grit our teeth and deal with it," Davison said.

"You dread the heat, but it is also a little bit exciting because it sorts the men from the boys. It will be only the tough that survive, and will come down to who is mentally the strongest.

"You need the mind power to push through the pain and it will hurt but they are the races that give you the most satisfaction."

The only relief for the drivers comes from a device called a cool suit - a vest that circulates cold water through a system of pipes. But they sometimes fail, pushing hot water over the body instead.

"It is dreadful when the cool suits fail," Davison said.

"But even with them on there are health concerns because this is hard-core stuff. "No-one will get to the end without a cool suit. I definitely think you will see drivers getting taken out of the cars and taken away in the back of an ambulance."

Holden's James Courtney said he was sent "loopy" by the heat at a race in 2009.

"You can get delusional," Courtney said.

"It happened to me when I was at DJR in 2009 at Clipsal. My cool suit failed and I started talking random junk on the radio.

"The team realised I had lost my marbles, was all loopy and brought me in. That might happen to a couple of people this weekend."

Drivers are expecting to loose up to 5kg in the sweltering heat and the V8 medical team have a fridge full of saline intravenous drips on standby for extreme case of dehydration.

"The drivers must prepare for heat stress even before the race," said V8 medical chief Dr Karl Lee.

"They will pre-cool themselves before the race and you will find them in ice baths, some even in food freezers. It has been found that this preparation helps.

"They also drink litres and litres of water the night before in a bid to keep hydrated.

"For us we look for signs of heat stress and the first is with their communication.

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